The realities of optical network design

The past 10 years have seen extraordinary leaps in the capacity of optical networks, mainly because of the dense wavelength-division multiplexing (DWDM) revolution. Indeed, the ability of this technique to boost the capacity of long-haul networks while reducing network equipment costs produced a rush to implement the technology in metropolitan and campus networks. The cost/capacity formula turned out to be less favorable in shorter networks with many nodes, but the race was on to build all-optical switches that potentially could extend the long-haul capacity revolution to the desktop.

Conventional analysis held that all-optical networks, while initially more expensive because of the high return on investment resulting from new technology development, would clearly prove cheaper in the long run as the clear capacity and speed advantages of all-optical technology took hold. And the rosy economic projections of the 1990s built confidence in that scenario. But the current economic climate is close to the exact inverse of those expectations, causing technologists to take a much harder look at costs in the push toward all-optical switching.

In this week's In Focus, engineers grappling with the new realities of optical network design provide a more guarded assessment. New ideas are still percolating out there, and all-optical networking may, in the long run, still turn out to be the winning card. But getting there may be more difficult than anticipated.

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